The present invention, in one aspect, relates to compounds in which the inhibition, regulation and/or modulation of kinase signal transduction, in particular tyrosine kinase and Raf kinase signal transduction, plays a role, furthermore to pharmaceutical compositions which comprise these compounds, and to the use of the compounds for the treatment of tyrosine kinase-induced diseases.
In other aspects, the present invention relates to compounds which inhibit, regulate and/or modulate tyrosine kinase signal transduction, to compositions which comprise these compounds, and to methods for the use thereof for the treatment of tyrosine kinase-induced diseases and conditions, such as cancer, tumour growth, arteriosclerosis, age-related macular degeneration, diabetic retinopathy, inflammatory diseases and the like, in mammals.
Tyrosine kinases are a class of enzymes which catalyse the transfer of the terminal phosphate of adenosine triphosphate to tyrosine residues in protein substrates. Tyrosine kinases, through substrate phosphorylation, play a crucial role in signal transduction for a number of cellular functions. Although the precise mechanisms of signal transduction are still unclear, tyrosine kinases have been shown to be important contributing factors in cell proliferation, carcinogenesis and cell differentiation.
Tyrosine kinases can be categorised as receptor-type tyrosine kinases or non-receptor-type tyrosine kinases. Receptor-type tyrosine kinases have an extracellular portion, a transmembrane portion and an intracellular portion, while non-receptor-type tyrosine kinases are exclusively intracellular. Receptor-type tyrosine kinases contain a multiplicity of transmembrane receptors with different biological activity. Thus, about 20 different sub-families of receptor-type tyrosine kinases have been identified. One tyrosine kinase subfamily, known as the HER subfamily, consists of EGFR, HER2, HER3 and HER4. Ligands from this subfamily of receptors include epithelial growth factor, TGF-α, amphiregulin, HB-EGF, betacellulin and heregulin. Another subfamily of these receptor-type tyrosine kinases is the insulin subfamily, which includes INS-R, IGF-IR and IR-R. The PDGF subfamily includes the PDGF-α and -β receptors, CSFIR, c-kit and FLK-II. In addition, there is the FLK family, which consists of the kinase insert domain receptor (KDR), foetal liver kinase-1 (FLK-1), foetal liver kinase-4 (FLK-4) and fms tyrosine kinase-1 (flt-1). The PDGF and FLK families are usually discussed together due to the similarities between the two groups. For a detailed discussion of receptor-type tyrosine kinases, see Plowman et al., DN & P 7(6):334-339, 1994, which is hereby incorporated by way of reference.
Non-receptor-type tyrosine kinases likewise contain a multiplicity of sub-families, including Src, Frk, Btk, Csk, Abl, Zap70, Fes/Fps, Fak, Jak, Ack and LIMK. Each of these subfamilies is further sub-divided into different receptors. For example, the Src subfamily is one of the largest subfamilies. It includes Src, Yes, Fyn, Lyn, Lck, Blk, Hck, Fgr and Yrk. The Src sub-family of enzymes has been linked to oncogenesis. For a more detailed discussion of non-receptor-type tyrosine kinases, see Bolen Oncogene, 8:2025-2031 (1993), which is hereby incorporated by way of reference. Both receptor-type tyrosine kinases and non-receptor-type tyrosine kinases are involved in cellular signalling pathways leading to numerous pathogenic conditions, including cancer, psoriasis and hyperimmune responses.
Various receptor-type tyrosine kinases, and the growth factors binding to them, play a role in angiogenesis, although some may promote angiogenesis indirectly (Mustonen and Alitalo, J. Cell Biol. 129:895-898, 1995). One of these receptor-type tyrosine kinases is foetal liver kinase 1, also referred to as FLK-1. The human analogue of FLK-1 is the kinase insert domain-containing receptor KDR, which is also known as vascular endothelial cell growth factor receptor 2 or VEGFR-2, since it binds VEGF with high affinity. Finally, the murine version of this receptor has also been called NYK (Oelrichs et al., Oncogene 8(1):11-15, 1993). VEGF and KDR are a ligand-receptor pair which plays a vital role in the proliferation of vascular endothelial cells and the formation and sprouting of blood vessels, referred to as vasculogenesis and angiogenesis respectively.
Angiogenesis is characterised by excessive activity of vascular endothelial growth factor (VEGF). VEGF contains a family of ligands (Klagsburn and D'Amore, Cytokine & Growth Factor Reviews 7:259-270, 1996). VEGF binds the high affinity membrane-spanning tyrosine kinase receptor KDR and the related fms tyrosine kinase-1, also known as Flt-1 or vascular endothelial cell growth factor receptor 1, (VEGFR-1). Cell culture and gene knockout experiments indicate that each receptor contributes to different aspects of angiogenesis. KDR mediates the mitogenic function of VEGF, whereas Flt-1 appears to modulate non-mitogenic functions, such as those associated with cellular adhesion. Inhibiting KDR thus modulates the level of mitogenic VEGF activity. In fact, tumour growth has been shown to be susceptible to the antiangiogenic effects of VEGF receptor antagonists (Kim et al., Nature 362, pp. 841-844, 1993).
Solid tumours can therefore be treated with tyrosine inhibitors since these tumours depend on angiogenesis for the formation of the blood vessels that are necessary to support their growth. These solid tumours include monocytic leukaemia, carcinomas of the brain, urogenital tract, lymphatic system, stomach, larynx and lung, including lung adenocarcinoma and small cell lung carcinoma. Further examples include carcinomas in which overexpression or activation of Raf-activating oncogenes (for example, K-ras, erb-B) is observed. Such carcinomas include pancreatic and breast carcinoma. Inhibitors of these tyrosine kinases are therefore suitable for the prevention and treatment of proliferative diseases caused by these enzymes.
The angiogenic activity of VEGF is not limited to tumours. VEGF accounts for the angiogenic activity produced in or near the retina in diabetic retinopathy. This vascular growth in the retina leads to visual degeneration culminating in blindness. Ocular VEGF mRNA and protein levels are elevated by conditions such as retinal vein occlusion in primates and decreased pO2 levels in mice that lead to neovascularisation. Intraocular injections of anti-VEGF monoclonal antibodies or VEGF receptor immunofusions inhibit ocular neovascularisation in both primate and rodent models. Irrespective of the cause of induction of VEGF in human diabetic retinopathy, inhibition of ocular VEGF is suitable for treating this disease.
Expression of VEGF is also significantly increased in hypoxic regions of animal and human tumours adjacent to areas of necrosis. In addition, VEGF is upregulated by the expression of the oncogenes Ras, Raf, Src and mutant p53 (all of which are relevant in combating cancer). Anti-VEGF monoclonal antibodies inhibit the growth of human tumours in nude mice. Although the same tumour cells continue to express VEGF in culture, the antibodies do not diminish their mitotic rate. Thus, tumour-derived VEGF does not function as an autocrine mitogenic factor. VEGF therefore contributes to tumour growth in vivo by promoting angiogenesis through its paracrine vascular endothelial cell chemotactic and mitogenic activities. These monoclonal antibodies also inhibit the growth of typically less well vascularised human colon carcinomas in athymic mice and decrease the number of tumours arising from inoculated cells.
The expression of a VEGF-binding construct of Flk-1, Flt-1, the mouse KDR receptor homologue truncated to eliminate the cytoplasmic tyrosine kinase domains but retaining a membrane anchor, in viruses virtually stops the growth of a transplantable glioblastoma in mice, presumably by the dominant negative mechanism of heterodimer formation with membrane-spanning endothelial cell VEGF receptors.
Embryonic stem cells, which normally grow as solid tumours in nude mice, do not produce detectable tumours if both VEGF alleles are knocked out. Taken together, these data indicate the role of VEGF in the growth of solid tumours. Inhibition of KDR or Flt-1 is involved in pathological angiogenesis, and these receptors are suitable for the treatment of diseases in which angiogenesis is part of the overall pathology, for example inflammation, diabetic retinal vascularisation, as well as various forms of cancer, since tumour growth is known to be dependent on angiogenesis (Weidner et al., N. Engl. J. Med., 324, pp. 1-8, 1991).
The present invention furthermore relates to the compounds as inhibitors of Raf kinases.
Protein phosphorylation is a fundamental process for the regulation of cellular functions. The coordinated action of both protein kinases and phosphatases controls the degrees of phosphorylation and, hence, the activity of specific target proteins. One of the predominant roles of protein phosphorylation is in signal transduction, where extracellular signals are amplified and propagated by a cascade of protein phosphorylation and dephosphorylation events, for example in the p21ras/Raf pathway.
The p21ras gene was discovered as an oncogene of the Harvey (H-Ras) and Kirsten (K-Ras) rat sarcoma viruses. In humans, characteristic mutations in the cellular Ras gene (c-Ras) have been associated with many different types of cancer. These mutant alleles, which render Ras constitutively active, have been shown to transform cells, such as, for example, the murine cell line NIH 3T3, in culture.
The p21ras oncogene is a major contributor to the development and progression of human solid carcinomas and is mutated in 30% of all human carcinomas (Bolton et al. (1994) Ann. Rep. Med. Chem., 29, 165-74; Bos. (1989) Cancer Res., 49, 4682-9). In its normal, unmutated form, the Ras protein is a key element of the signal transduction cascade directed by growth factor receptors in almost all tissues (Avruch et al. (1994) Trends Biochem. Sci., 19, 279-83).
Biochemically, Ras is a guanine nucleotide binding protein, and cycling between a GTP-bound activated and a GDP-bound resting form is strictly controlled by Ras endogenous GTPase activity and other regulatory proteins. The Ras gene product binds to guanine triphosphate (GTP) and guanine diphosphate (GDP) and hydrolyses GTP to GDP. Ras is active in the GTP-bound state. In the Ras mutants in cancer cells, the endogenous GTPase activity is reduced and the protein consequently transmits constitutive growth signals to downstream effectors, such as, for example, the enzyme Raf kinase. This leads to the cancerous growth of the cells which carry these mutants (Magnuson et al. (1994) Semin. Cancer Biol., 5, 247-53). The Ras proto-oncogene requires a functionally intact C-Raf-1 protooncogene in order to transduce growth and differentiation signals initiated by receptor- and non-receptor-type tyrosine kinases in higher eukaryotes.
Activated Ras is necessary for the activation of the C-Raf-1 proto-oncogene, but the biochemical steps through which Ras activates the Raf-1 protein (Ser/Thr) kinase are now well characterised. It has been shown that inhibiting the effect of active Ras by inhibiting the Raf kinase signalling pathway by administration of deactivating antibodies to Raf kinase or by co-expression of dominant negative Raf kinase or dominant negative MEK (MAPKK), the substrate of Raf kinase, leads to reversion of transformed cells to the normal growth phenotype, see: Daum et al. (1994) Trends Biochem. Sci., 19, 474-80; Fridman et al. (1994) J Biol. Chem., 269, 30105-8. Kolch et al. (1991) Nature, 349, 426-28 and for a review Weinstein-Oppenheimer et al. Pharm. & Therap. (2000), 88, 229-279.
Similarly, inhibition of Raf kinase (by antisense oligodeoxynucleotides) has been correlated in vitro and in vivo with inhibition of the growth of a variety of human tumour types (Monia et al., Nat. Med. 1996, 2, 668-75).
Raf serine- and threonine-specific protein kinases are cytosolic enzymes that stimulate cell growth in a variety of cellular systems (Rapp, U. R., et al. (1988) in The Oncogene Handbook; T. Curran, E. P. Reddy and A. Skalka (eds.) Elsevier Science Publishers; The Netherlands, pp. 213-253; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184; Rapp, U. R., et al. (1990) Inv Curr. Top. Microbiol. Immunol. Potter and Melchers (eds.), Berlin, Springer-Verlag 166:129-139).
Three isozymes have been characterised: C-Raf (Raf-1) (Bonner, T. I., et al. (1986) Nucleic Acids Res. 14:1009-1015). A-Raf (Beck, T. W., et al. (1987) Nucleic Acids Res. 15:595-609) and B-Raf (Qkawa, S., et al. (1998) Mol. Cell. Biol. 8:2651-2654; Sithanandam, G. et al. (1990) Oncogene: 1775). These enzymes differ in their expression in various tissues. Raf-1 is expressed in all organs and in all cell lines that have been examined, and A- and B-Raf are expressed in urogenital and brain tissues respectively (Storm, S. M. (1990) Oncogene 5:345-351).
Raf genes are proto-oncogenes can initiate malignant transformation of cells when expressed in specifically altered forms. Genetic changes that lead to oncogenic activation generate a constitutively active protein kinase by removal of or interference with an N-terminal negative regulatory domain of the protein (Heidecker, G., et al. (1990) Mol. Cell. Biol. 10:2503-2512; Rapp, U. R., et al. (1987) in Oncogenes and Cancer; S. A. Aaronson, J. Bishop, T. Sugimura, M. Terada, K. Toyoshima and P. K. Vogt (eds.) Japan Scientific Press, Tokyo). Microinjection into NIH 3T3 cells of oncogenically activated, but not wild-type, versions of the Raf protein prepared with Escherichia coli expression vectors results in morphological transformation and stimulates DNA synthesis (Rapp, U. R., et al. (1987) in Oncogenes and Cancer; S. A. Aaronson, J. Bishop, T. Sugimura, M. Terada, K. Toyoshima and P. K. Vogt (ed.) Japan Scientific Press, Tokyo; Smith, M. R., et al. (1990) Mol. Cell. Biol. 10:3828-3833).
Consequently, activated Raf-1 is an intracellular activator of cell growth. Raf-1 protein serine kinase is a candidate for the downstream effector of mitogen signal transduction, since Raf oncogenes overcome growth arrest resulting from a block of cellular Ras activity due either to a cellular mutation (Ras revertant cells) or microinjection of anti-Ras antibodies (Rapp, U. R., et al. (1988) in The Oncogene Handbook, T. Curran, E. P. Reddy and A. Skalka (eds.), Elsevier Science Publishers; The Netherlands, pp. 213-253; Smith, M. R., et al. (1986) Nature (London) 320:540-543).
C-Raf function plays a role in transformation by a variety of membrane-bound oncogenes and for growth stimulation by mitogens contained in serums (Smith, M. R., et al. (1986) Nature (London) 320:540-543). Raf-1 protein serine kinase activity is regulated by mitogens via phosphorylation (Morrison, D. K., et al. (1989) Cell 58:648-657), which also effects sub-cellular distribution (Olah, Z., et al. (1991) Exp. Brain Res. 84:403; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184. Raf-1 activating growth factors include platelet-derived growth factor (PDGF) (Morrison, D. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859), colony-stimulating factor (Baccarini, M., et al. (1990) EMBO J. 9:3649-3657), insulin (Blackshear, P. J., et al. (1990) J. Biol. Chem. 265:12115-12118), epidermal growth factor (EGF) (Morrison, R. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859), interleukin-2 (Turner, B. C., et al. (1991) Proc. Natl. Acad. Sci. USA 88:1227) and interleukin-3 and granulocyte macrophage colony-stimulating factor (Carroll, M. P., et al. (1990) J. Biol. Chem. 265:19812-19817).
After mitogen treatment of cells, the transiently activated Raf-1 protein serine kinase translocates to the perinuclear area and the nucleus (Olah, Z., et al. (1991) Exp. Brain Res. 84:403; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184). Cells containing activated Raf are altered in their pattern of gene expression (Heidecker, G., et al. (1989) in Genes and signal transduction in multistage carcinogenesis, N. Colburn (ed.), Marcel Dekker, Inc., New York, pp. 339-374) and Raf oncogenes activate transcription from Ap-I/PEA3-dependent promoters in transient transfection assays (Jamal, S., et al. (1990) Science 344:463-466; Kaibuchi, K., et al. (1989) J. Biol. Chem. 264:20855-20858; Wasylyk, C., et al. (1989) Mol. Cell. Biol. 9:2247-2250).
There are at least two independent pathways for Raf-1 activation by extra-cellular mitogens: one involving protein kinase C (KC) and a second initiated by protein tyrosine kinases (Blackshear, P. J., et al. (1990) J. Biol. Chem. 265:12131-12134; Kovacina, K. S., et al. (1990) J. Biol. Chem. 265:12115-12118; Morrison, D. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859; Siegel, J. N., et al. (1990) J. Biol. Chem. 265:18472-18480; Turner, B. C., et al. (1991) Proc. Natl. Acad. Sci. USA 88:1227). In each case, activation involves Raf-1 protein phosphorylation. Raf-1 phosphorylation may be a consequence of a kinase cascade amplified by auto-phosphorylation or may be caused entirely by autophosphorylation initiated by binding of a putative activating ligand to the Raf-1 regulatory domain, analogous to PKC activation by diacylglycerol (Nishizuka, Y. (1986) Science 233:305-312).
One of the principal mechanisms by which cellular regulation is effected is through the transduction of extracellular signals across the membrane that in turn modulate biochemical pathways within the cell. Protein phosphorylation represents one course by which intracellular signals are propagated from molecule to molecule resulting finally in a cellular response. These signal transduction cascades are highly regulated and often overlap, as is evident from the existence of many protein kinases as well as phosphatases. Phosphorylation of proteins occurs predominantly at serine, threonine or tyrosine residues, and protein kinases have therefore been classified by their specificity of phosphorylation site, i.e. serine/threonine kinases and tyrosine kinases. Since phosphorylation is such a ubiquitous process within cells and since cellular phenotypes are largely influenced by the activity of these pathways, it is currently believed that a number of disease states and/or diseases are attributable to either aberrant activation or functional mutations in the molecular components of kinase cascades. Consequently, considerable attention has been devoted to the characterisation of these proteins and compounds that are able to modulate their activity (for a review see: Weinstein-Oppenheimer et al. Pharma. &. Therap., 2000, 88, 229-279).
The protein kinase PKB (also known as AKT and RAC-PK) is a member of the AKT/PKB family of serine/threonine kinases and has been shown to be involved in a diverse set of signalling pathways in human malignancy (Nicholson et al., Cell. Signal., 2002, 14, 381-395). PKB, like other members of the AKT/PKB family, is located in the cytosol of unstimulated cells and translocates to the cell membrane following stimulation. PKB translocation can be activated by a number of ligands, including platelet-derived growth factor, epidermal growth factor, basic fibroblast growth factor, cellular stress, such as, for example, heat shock and hyperosmolarity, as well as insulin (Bos, Trends Biochem. Sci., 1995, 20, 441-442), and other studies have shown that this activation is through PI3 kinase which is wortmannin-sensitive (Franke et al., Science, 1997, 275, 665-668). Once located on the plasma membrane, PKB has been shown to mediate several functions within the cell, including apoptosis, the metabolic effects of insulin, induction of differentiation and/or proliferation, protein synthesis and stress responses (Alessi and Cohen, Curr. Opin. Genet. Dev., 1998, 8, 55-62; Downward, Curr. Opin. Cell Biol., 1998, 10, 262-267). PKB was cloned independently in 1991 by three groups (Bellacosa et al., Science, 1991, 254, 274-277; Coffer and Woodgett, Eur. J. Biochem., 1991, 201, 475-481; Jones et al., Cell Regul., 1991, 2, 1001-1009), but its association with primary human gastric carcinoma was recognised as early as 1987 (Staal et al., Proc. Natl. Acad. Sci. USA, 1987, 84, 5034-5037). Sequencing of PKBα revealed homology within the kinase domains to the PKA (about 68%) and PKC isozymes (about 73%) (Jones et al., Proc. Natl. Acad. Sci. U.S.A., 1991, 88, 4171-5), a fact that led to its renaming as PKB. There are three cellular isoforms of PKB and two splice variants (PKBα, β, γ, β1, γ1; Brazil et al. Trends in Bio Sci, 2001, 26, 657-663). PKBα was found to be amplified or overexpressed in gastric adenocarcinomas and in a breast cancer cell line (Staal et al., Proc. Natl. Acad. Sci. U.S.A., 1987, 84, 5034-7; Jones et al., Cell Regul., 1991, 2, 1001-9). PKBβ is amplified or overexpressed in 3% of breast (Bellacosa et al., Int. J. Cancer, 1995 64, 280-5), 12% of pancreatic (Cheng et al., Proc. Natl. Acad. Sci. U.S.A., 1996, 93, 3636-41) and 15% of ovarian cancers (Bellacosa et al., Int. J. Cancer, 1995, 64, 280-5; Cheng et al., Proc. Natl. Acad. Sci. U.S.A., 1992, 89, 9267-71).
PKBγ is overexpressed in oestrogen receptor-deficient breast cancer and in androgen-independent prostate cell lines (Nakatani et al., J. Biol. Chem. 199, 274, 21528-32).
It has been proposed that PKB is a gene which is involved in chromosomal rearrangement at chromosome band 14q32. This locus is known to undergo rearrangement in human T-cell malignancies, such as, for example, prolymphocytic leukaemias and mixed lineage childhood leukaemias (Staal et al., Genomics, 1988, 2, 96-98).
PKB also plays a role in the prevention of “programmed cell death” or apoptosis by inhibitory phosphorylation of ASK-1, Bad, Caspase9 and FKHR (for review see Nicholson et al., Cell Signalling 2001, 14, 281-395). It has been shown that PKB provides cells with a survival signal (for review see Lawlor et al., J. of Cell Science 2001, 114, 2903-2910) in order to protect them from a number of agents, including UV radiation (Dudek et al., Science, 1997, 275, 661-665), withdrawal of IGF1 from neuronal cells, detachment from the extracellular matrix, stress and heat shock (Alessi and Cohen, Curr. Opin. Genet. Dev., 1998, 8, 55-62).
The dual-specific phosphatase PTEN (phosphatase and tensin homologue deleted on chromosome ten) increases the Ptdlns(3, 4, 5)P3 level in the cell by dephosphorylation of Ptdlns(3, 4, 5)P3. Ptdlns(3, 4, 5)P3 binds to the PH domain (Pleckstrin homology domain) of PKB. This binding is an essential step for membrane translocation and activation of PKB. PTEN is a tumour suppressor gene mutated in a large proportion of glioblastoma and melanoma cell lines, advanced prostate carcinomas and endometrial carcinomas. Furthermore, it is deleted in >80% of patients with hereditary conditions, such as, for example, Cowden's disease, Lhermitte-Ducios syndrome and Bannayan-Zonana syndrome. The patients display a number of similar features, including multiple benign tumours (harmatomas) and increased susceptibility to breast and thyroid malignancies (Di Cristofano at al. Cell, 2000, 100, 387-390).
Cell lines derived from PTEN+/− heterozygous mice (PTEN−/− heterozygous mice are not viable) show increased Ptdlns(3, 4, 5)P3 levels paralleled by increased PKB activity, with concomitant decreased sensitivity to apoptosis (Di Christofano et al. Nat. Genet. 1998, 19, 348-355; Stambolic at al., Cell, 1998, 95, 29-39, Myers et al., Proc. Natl. Acad. Si. U.S.A., 1998, 96 13513-13518).
PKB is also able to promote cell cycle progression by inhibiting p21 cell cycle inhibitor (Zhou et al.; Nat. Cell Biol., 2002,3, 245-252).
These findings may explain the overexpression of PKB observed in cancer cells which allows preferential survival and proliferation of the carcinomas by preventing the normal progression to apoptosis.
At present, there are no known therapeutic agents which effectively inhibit the activity of PKB. Consequently, there remains a long felt need for agents which are capable of effectively inhibiting PKB function for the activation of pro-apoptotic proteins in all kinds of cancer as chemotherapeutic agents.
The identification of small compounds which specifically inhibit, regulate and/or modulate signal transduction of tyrosine kinases and/or Raf kinases is therefore desirable and an aim of the present invention.
It has been found that the compounds of the formula I and salts and solvates thereof have very valuable pharmacological properties while being well tolerated. In particular, they exhibit tyrosine kinase inhibiting properties.
It has furthermore been found that the compounds of the formula I, and salts and solvates thereof, which are generally described as chromenone derivatives, are inhibitors of the enzyme Raf kinase. Since the enzyme is a downstream effector of p21ras, the inhibitors prove to be suitable in pharmaceutical compositions for use in human or veterinary medicine where inhibition of the Raf kinase pathway is indicated, for example in the treatment of tumours and/or cancerous cell growth mediated by Raf kinase. In particular, the compounds are suitable for the treatment of human and animal solid cancers, for example murine cancer, since the progression of these cancers is dependent upon the Ras protein signal transduction cascade and therefore susceptible to treatment by interruption of the cascade, i.e. by inhibiting Raf kinase. Accordingly, the compound of the formula I or a pharmaceutically acceptable salt or solvate thereof is administered for the treatment of diseases mediated by the Raf kinase pathway, especially cancer, including solid cancers, such as, for example, carcinomas (for example of the lungs, pancreas, thyroid, bladder or colon), myeloid diseases (for example myeloid leukaemia) or adenomas (for example villous colon adenoma), pathological angiogenesis and metastatic cell migration. The compounds are furthermore suitable for the treatment of complement activation dependent chronic inflammation (Niculescu et al. (2002) Immunol. Res., 24:191-199) and HIV-1 (human immunodeficiency virus type 1) induced immunodeficiency (Popik et al. (1998) J Virol, 72: 6406-6413).
Surprisingly, it has been found that compounds according to the invention are able to interact with signalling pathways, especially the signalling pathways described herein and preferably the Raf kinase signalling pathway. Chromenone derivatives according to the invention preferably exhibit an advantageous biological activity which is easily demonstrated in enzyme-based assays, for example assays as described herein. In such enzyme-based assays, chromenone derivatives according to the invention exhibit an effect, preferably an inhibiting effect, which is usually documented by IC50 values in a suitable range, preferably in the micromolar range and more preferably in the nanomolar range.
As discussed herein, these signalling pathways are relevant for various diseases. Accordingly, chromenone derivatives are suitable for the prophylaxis and/or treatment of diseases that are dependent on the said signalling pathways by interacting with one or more of the said signalling pathways.
The present invention therefore in one aspect relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of the signalling pathways described herein. The invention therefore preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of the Raf kinase pathway. The invention therefore more preferably relates to derivatives according to the invention as promoters or inhibitors, preferably as inhibitors, of Raf kinase. The invention still more preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of one or more Raf kinases selected from the group consisting of A-Raf, B-Raf and C-Raf-1. The invention particularly preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of C-Raf-1.
The present invention furthermore relates to the use of one or more compounds according to the invention in the treatment and/or prophylaxis of diseases, preferably the diseases described herein, that are caused, mediated and/or propagated by Raf kinases and in particular diseases that are caused, mediated and/or propagated by Raf kinases selected from the group consisting of A-Raf, B-Raf and C-Raf-1. The diseases discussed herein are usually divided into two groups, hyperproliferative and non-hyperproliferative diseases. In this connection, psoriasis, arthritis, inflammation, endometriosis, scarring, benign prostatic hyperplasia, immunological diseases, autoimmune diseases and immunodeficiency diseases are to be regarded as non-cancerous diseases, of which arthritis, inflammation, immunological diseases, autoimmune diseases and immunodeficiency diseases are usually regarded as non-hyperproliferative diseases. In this connection, brain cancer, lung cancer, squamous cell cancer, bladder cancer, gastric cancer, pancreatic cancer, hepatic cancer, renal cancer, colorectal cancer, breast cancer, head cancer, neck cancer, oesophageal cancer, gynaecological cancer, thyroid cancer, lymphoma, chronic leukaemia and acute leukaemia are to be regarded as cancerous diseases, all of which are usually regarded as hyperproliferative diseases. Especially cancerous cell growth and especially cancerous cell growth mediated by Raf kinase is a disease which is a target of the present invention. The present invention therefore relates to compounds according to the invention as medicaments and/or medicament active ingredients in the treatment and/or prophylaxis of the said diseases and to the use of compounds according to the invention for the preparation of a pharmaceutical for the treatment and/or prophylaxis of the said diseases as well as to a method for the treatment of the said diseases which comprises the administration of one or more compounds according to the invention to a patient in need of such an administration.
In a comparative measurement, it has furthermore been found that the compounds of the formula I act as PKB inhibitors. This action can be demonstrated, for example, by a method described by Alessi et al. EMBO L. 1996, 15, 6541-6551.
It can be shown that the compounds according to the invention have an antiproliferative action in vivo. The compounds according to the invention are administered to a patient having a hyperproliferative disease, for example to inhibit tumour growth, to reduce inflammation associated with a lymphoproliferative disease, to inhibit transplant rejection or neurological damage due to tissue repair, etc. The present compounds are suitable for prophylactic or therapeutic purposes. As used herein, the term “treatment” is used to refer to treatment of pre-existing conditions. The prevention of proliferation is achieved by administration of the compounds according to the invention prior to the development of overt disease, for example to prevent the growth of tumours, prevent metastatic growth, diminish restenosis associated with cardiovascular surgery, etc. Alternatively, the compounds are used for the treatment of ongoing diseases by stabilising or improving the clinical symptoms of the patient.
The host or patient can belong to any mammalian species, for example a primate species, particularly humans; rodents, including mice, rats and hamsters; rabbits; horses, cows, dogs, cats, etc. Animal models are of interest for experimental investigations, providing a model for treatment of human disease.
The susceptibility of a particular cell to treatment with the compounds according to the invention can be determined by in vitro tests. Typically, a culture of the cell is combined with a compound according to the invention at various concentrations for a period of time which is sufficient to allow the active agents to induce cell death or to inhibit migration, usually between about one hour and one week. In vitro testing can be carried out using cultivated cells from a biopsy sample. The viable cells remaining after the treatment are then counted.
The dose varies depending on the specific compound used, the specific disease, the patient status, etc. A therapeutic dose is typically sufficient considerably to reduce the undesired cell population in the target tissue while the viability of the patient is maintained. The treatment is generally continued until a considerable reduction has occurred, for example an at least about 50% reduction in the cell burden, and may be continued until essentially no more undesired cells are detected in the body.
For the identification of kinase inhibitors, various assay systems are available. In scintillation proximity assay (Sorg et al., J. of. Biomolecular Screening, 2002, 7, 11-19) and flashplate assay, the radioactive phosphorylation of a protein or peptide as substrate with γATP is measured. In the presence of an inhibitory compound, a decreased radioactive signal, or none at all, is detectable. Furthermore, homogeneous time-resolved fluorescence resonance energy transfer (HTR-FRET) and fluorescence polarisation (FP) technologies are suitable as assay methods (Sills et al., J. of Biomolecular Screening, 2002, 191-214).
Other non-radioactive ELISA assay methods use specific phospho-antibodies (phospho-ABs). The phospho-AB binds only the phosphorylated substrate. This binding can be detected by chemiluminescence using a second peroxidase-conjugated anti-sheep antibody (Ross et al., 2002, Biochem. J., just about to be published, manuscript BJ20020786).
There are many diseases associated with deregulation of cellular proliferation and cell death (apoptosis). The conditions of interest include, but are not limited to, the following. The compounds according to the invention are suitable for the treatment of a number of conditions where there is proliferation and/or migration of smooth muscle cells and/or inflammatory cells into the intimal layer of a vessel, resulting in restricted blood flow through that vessel, for example in the case of neointimal occlusive lesions. Occlusive vascular diseases of interest include atherosclerosis, graft coronary vascular disease after transplantation, vein graft stenosis, peri-anastomatic prosthetic restenosis, restenosis after angioplasty or stent placement, and the like.
The compounds according to the invention are, in addition, suitable as food supplements, for the treatment of diseases and/or dysfunctions which are characterised by oxidative stress conditions and as sunscreens in cosmetic formulations.